No explanation needed, my log is attached. I have already tried downgrading, downloaded from Modrinth.
crash.txt

Meant to post this on the CreativeCore GitHub page, my bad!

Seems like there is an issue with the library sgui (https://github.com/Patbox/sgui). It is used by the Mod Viewer mod. If you can remove this mod and see if it will work.

I got everything working. I removed Mod Viewer and still couldn't start Minecraft unless the Essentials mod was removed for some reason. Thank you!

Good to know. Glad you got it working!